1. Field of the Invention
The present invention relates to an image forming apparatus which transfers a toner image formed on an image carrier to a recording medium with a transfer device and separates the recording medium from the image carrier by discharging to the recording medium by means of a discharging device. The invention is more particularly related to an image forming apparatus which includes a support member supporting the transfer device, which bends or folds at a hinged region to form a relatively large space between the transfer device and the image carrier for facilitating clearance of a jammed sheet
2. Discussion of the Background
As an image forming apparatus which transfers a toner image formed on an image carrier to a recording medium with a transfer device and separates the recording medium from the image carrier by discharging the recording medium with a discharging device, there are known various image forming apparatuses such as a copying machine, a printer, a facsimile machine and a multi-function machine having copying, facsimile and printer functions. In these apparatuses, a recording medium which is a sheet is conveyed to a transfer area between an image carrier and a transfer device. A toner image formed on the image carrier is transferred to the recording medium using of the transfer device and the recording medium is then separated from the image carrier by discharging the recording medium using the discharging device.
While a recording medium is conveyed along a predetermined conveying path in these apparatuses, a paper jam or other conveying trouble sometimes occurs in the transfer area or in an area near the transfer area. Therefore, in a conventional image forming apparatus, a transfer device is generally constructed so as to be separable from the image carrier so that a recording medium jammed in the transfer area or in an area near the transfer area can be easily taken out of such areas. For example, a support member of a transfer device is mounted to a main body of an image forming apparatus so as to swing open relative to the main body. The transfer device is usually supported in a position facing the image carrier by this support member, and is separated from the image carrier when a recording medium is jammed in a transfer area or in an area near the transfer area, by swinging open the support member relative to the main body of the apparatus. The transfer device supported by the support member is thus separated from the image carrier to form a space between the transfer device and the image carrier, thereby enabling a person to insert his or her hands into that space for removing the recording medium which is jammed between the transfer device and the image carrier.
However, there are provided around the transfer device various elements such as a base plate of the main body of the apparatus, and it is rather difficult to form a large space between the transfer device and the image carrier for clearing a recording medium which is jammed in the transfer area or in the area near the transfer area, even when the support member of the transfer device is so constructed to swing open relative to the main body as described above. Especially, a size of recent image forming apparatus tends to become smaller and consequently, a space allowed for clearing a jammed recording medium tends to become narrower. It is not so easy to insert a hand into such a narrow space for clearing a jammed recording medium, and not only efficiency of clearing a jammed recording medium lowers but also there exist possibilities that the hands and clothes of an operator will be stained with toner, and also possibilities that parts of the apparatus are touched by the operator will become damaged.
Further, a transfer device which is constituted of, for example, a transfer roller contacting an image carrier or a corona charger facing and separated from an image carrier, when used for a long period of time, deteriorates in its properties. If such a deteriorated transfer device is continued to be used, an abnormal image is produced. Therefore, a transfer device needs to be regularly cleaned and checked, and be replaced with a new device when the expected life span of the device expires.
A conventional image forming apparatus is therefore so constructed that a transfer device is detached from its support member by pulling the transfer device towards a front position of the apparatus and is mounted to the support member of the transfer device by pushing back the transfer device toward a rear position of the apparatus. Namely, an operator pulls the transfer device towards a front position of the apparatus when cleaning or checking the transfer device or replacing the device with a new device, and pushes back the transfer device, after cleaning or checking the new device, towards a rear position of the apparatus to mount the transfer device to the support member.
With the above-mentioned construction, however, it is necessary to contain the transfer device in a holding case which is a separate unit from the support member for the transfer device and to mount the holding case detachably to the support member for the transfer device. Therefore, the number of parts increases and consequently the cost of the apparatus inevitably rises.
A discharging device also, when used for a long period of time, deteriorates in its property, and if such a deteriorated discharging device is continued to be used, an abnormal image is produced. Therefore, a discharging device also needs to be regularly cleaned and checked, and be replaced with a new device when the expected life span expires like a transfer device.
Therefore, in conventional image forming apparatuses, a transfer device and a discharging device are integrated in one unit so that the transfer device and the discharging device can be taken out of a main body of the apparatus integrally for repairing or replacement. The transfer device and the discharging device which are repaired, or a new transfer device and a new discharging device are integrally mounted to a main body of the apparatus.
Thus, even in a conventional image forming apparatus, a transfer device and a discharging device can be checked, cleaned or replaced with a new device when the expected life span is expired, because the transfer device and the discharging device are detachably mounted to a main body of the apparatus. However, a cycle of checking and cleaning or replacement of a transfer device is generally different from that of a discharging device, and the cycle of the discharging device is generally shorter than that of the transfer device. In such a case, it occurs that the transfer device needs not to be replaced with a new device because the life span is not yet expired when the discharging device needs to be replaced with a new device because of expiration of its life span.
In such a case, with the above-mentioned image forming apparatus, the discharging device cannot be removed alone from the main body of the apparatus for replacement because the transfer device and the discharging device are assembled integrally and mounted to the main body of the apparatus as an integrated unit.
When only the discharging device needs to be cleaned also, the transfer device which needs not be cleaned has to be removed from the main body of the apparatus and unnecessary work is forced.
Further, there is a known image forming apparatus in which a transfer device and a discharging device are individually mounted to a main body of the apparatus so that these devices can be detached from the main body individually. With such an image forming apparatus, when the life span of the transfer device is not expired and only the life span of the discharging device is expired, the discharging device alone can be detached from the apparatus for replacement. Namely, either the discharging device or the transfer device can be checked, cleaned or replaced with a new device.
With the above-mentioned construction, however, a transfer device and a discharging device have to be removed from a main body of the apparatus individually and therefore, when both devices need to detached from the apparatus, work for detaching these devices from the apparatus is complicated and work efficiency lowers. For example, when the life spans of the transfer device and the discharging device are both expired or both devices need to be checked and cleaned, these devices have to be detached from the apparatus individually and such work is onerous.